From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793213597; b=SljHCRwFjZPdlCanRo0KJZHlFBYyU7maF+39o7JCJHDHkZhSNM9VUi41PrgsWFiT7uG1 HDyKoMZO/VDLieGpRTCEqtHWnHBh5zhqn6TEO0laYVw/p8J+OQnE4l8BvleVg0lLO79JF 3w8oqohEZCipp1hxxs/wdYDaZ0oAk1jEc3hpYUSTj0N/UqdlsxJtsdPnhfqk9F3Xqz+35 X/Zf9jZBEwFDyU6cIehmP7mFBCW+/Qw1SZhqO4njpAf5wMpvKW52eKJT0Zps+f1KnoDov LYuNXF3hZl0GCV7YIygMQHCDL6w2kNp2tSvZfR7byQohq+azTrOPOt4K5c7OnhXxNmA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793213597; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=QMuO+dWTOncqJuOZCK1B0oCK7Hx+O9V4+ulWJzSC4zQ=; b=Q01XsJkDw2wGU5CQufYIi6zZtlMY7I5Okgec+Cq94vHjaH0yxv1OtnXA6vwahMR3ck9J 97UbSdoBnfvqsVGmyaHC3QptO/R2d89YBfvvWMRGK7/FHu5UwyjgMZ2NGKZgn0r/2l61P OwLvTdSXo+0YF3dc1B211BUI/Z5JyBGYwCv8mprzgjpk52yUwzXKbdJO3xCW+1QV+S7er Dbf//2BUC3Wm4ohKlSVMUSUIoJYegmp4ms0Ef0RiqEfOC+Rofq0Evu4f8hQqZKgeX1tAD Q+3XDBp9YlGGSIaEEMM06W5+NTmK3q2g1pLsU+Z5F0koD62njC0QBpiTxRcZXcQNchQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=F43h0FMB; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A491606A31F; Wed, 28 Oct 2026 18:53:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=F43h0FMB Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB42B1F01825; Wed, 28 Oct 2026 18:53:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793213597; bh=QMuO+dWTOncqJuOZCK1B0oCK7Hx+O9V4+ulWJzSC4zQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=F43h0FMBYa2edcblZAXZ5iRW4qbAPebpEyZt2GGWv7TNvpHG1NsQo6m4WCGQE1Fl2 fvLA+AKBF4iOLOWPdTcsdtRBqBjn8IrS+4Vmx91IkJ4Ivxm9ILqw6l2OE8w7lIFxtc 1EA1IHcIr/GVIr1rP26t3fC3oqMtGb4REzFC5vUo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Robert Richter , Dan Williams , Sasha Levin Subject: [PATCH 6.1 0561/1887] cxl/port: Fix delete_endpoint() vs parent unregistration race Date: Wed, 28 Oct 2026 17:44:17 +0100 Message-ID: <20261028170512.153626310@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams [ Upstream commit 8d2ad999ca3c64cb08cf6a58d227b9d9e746d708 ] The CXL subsystem, at cxl_mem ->probe() time, establishes a lineage of ports (struct cxl_port objects) between an endpoint and the root of a CXL topology. Each port including the endpoint port is attached to the cxl_port driver. Given that setup, it follows that when either any port in that lineage goes through a cxl_port ->remove() event, or the memdev goes through a cxl_mem ->remove() event. The hierarchy below the removed port, or the entire hierarchy if the memdev is removed needs to come down. The delete_endpoint() callback is careful to check whether it is being called to tear down the hierarchy, or if it is only being called to teardown the memdev because an ancestor port is going through ->remove(). That care needs to take the device_lock() of the endpoint's parent. Which requires 2 bugs to be fixed: 1/ A reference on the parent is needed to prevent use-after-free scenarios like this signature: BUG: spinlock bad magic on CPU#0, kworker/u56:0/11 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20230524-3.fc38 05/24/2023 Workqueue: cxl_port detach_memdev [cxl_core] RIP: 0010:spin_bug+0x65/0xa0 Call Trace: do_raw_spin_lock+0x69/0xa0 __mutex_lock+0x695/0xb80 delete_endpoint+0xad/0x150 [cxl_core] devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1d2/0x210 detach_memdev+0x15/0x20 [cxl_core] process_one_work+0x1e3/0x4c0 worker_thread+0x1dd/0x3d0 2/ In the case of RCH topologies, the parent device that needs to be locked is not always @port->dev as returned by cxl_mem_find_port(), use endpoint->dev.parent instead. Fixes: 8dd2bc0f8e02 ("cxl/mem: Add the cxl_mem driver") Cc: Reported-by: Robert Richter Closes: http://lore.kernel.org/r/20231018171713.1883517-2-rrichter@amd.com Signed-off-by: Dan Williams Signed-off-by: Sasha Levin --- drivers/cxl/core/port.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 20f052d3759e0..15b468b6aec38 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -1094,29 +1094,24 @@ static void delete_endpoint(void *data) { struct cxl_memdev *cxlmd = data; struct cxl_port *endpoint = dev_get_drvdata(&cxlmd->dev); - struct cxl_port *parent_port; - struct device *parent; + struct device *host = endpoint->dev.parent; - parent_port = cxl_mem_find_port(cxlmd, NULL); - if (!parent_port) - goto out; - parent = &parent_port->dev; - - device_lock(parent); - if (parent->driver && !endpoint->dead) { - devm_release_action(parent, cxl_unlink_uport, endpoint); - devm_release_action(parent, unregister_port, endpoint); + device_lock(host); + if (host->driver && !endpoint->dead) { + devm_release_action(host, cxl_unlink_uport, endpoint); + devm_release_action(host, unregister_port, endpoint); } - device_unlock(parent); - put_device(parent); -out: + device_unlock(host); put_device(&endpoint->dev); + put_device(host); } int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint) { + struct device *host = endpoint->dev.parent; struct device *dev = &cxlmd->dev; + get_device(host); get_device(&endpoint->dev); dev_set_drvdata(dev, endpoint); return devm_add_action_or_reset(dev, delete_endpoint, cxlmd); -- 2.53.0